共查询到19条相似文献,搜索用时 203 毫秒
1.
北三家拦河闸除险加固工程由溢流坝、冲砂闸和引水闸组成,工程主要作用是以灌溉为主的枢纽工程。经过长期运行,进水闸底部漏水严重,多处出现纵横裂缝,基础有不均匀沉降,两侧边墙有不同程度倾覆,闸门丢失及启闭机锈蚀严重。通过对进水闸进行水力计算,进而对进水闸进行除险加固设计,能够延长进水闸工程的使用年限,对充分发挥工程综合效益具有重要作用。 相似文献
2.
主要分析水电站进水口快速闸门在动水关闭过程中流量、临界开度和闸门受水流作用力(闸顶水压力、闸底水压力和闸门水平压力)等问题。根据模型试验所观测的水力现象和非恒定流计算理沦,提出了计算电站闸门、引水管道的水力参数(流量、水头和通气孔水位等)的数学模型。实例计算结果和模型试验结果基本吻合。 相似文献
3.
为解决柳沟拦河闸存在的安全问题,使其满足设计要求正常运行,全面分析了苏家屯区柳沟拦河闸存在的问题,通过设计暴雨、排涝模数、排涝流量、洪水成果合理性分析等计算拦河闸过流能力,并结合设计水面线计算结果校核了拦河闸断面水位.结果表明:拦河闸段20 a一遇过流能力为122.88 m3/s,10 a一遇过流能力为81.46 m3... 相似文献
4.
5.
南水北调中线输水渠道中,针对同时操作闸门是否仍能维持闸前水位为常值,模拟计算了同时改变渠首流量、闸门开度和分水口流量时渠道中的非恒定过渡过程。结果显示,中线主干渠中所有闸门开度不论是同时增加还是减小,渠道中的水流均需要很长时间才能达到新的恒定状态,且闸门开度减小比闸门开度增大所需的过渡时间要长很多。非恒定过渡过程中,闸前水位的变化幅度都较大,各闸前水位最终都能回复到初始时刻的水位。由于非恒定过渡过程时间很长,实际运行条件下,要实现闸前常水位运行方式还需要对闸门的调度方式做更多的研究。 相似文献
6.
在应用水力学公式推求过闸流量,或对闸门流量系数进行实测率定时,闸门开启高度(简称开高)是重要的水力因素,也是利用水工建筑物测流的基本观测项目,其观测精度对过闸流量或流量系数成果质量有决定性的影响。 相似文献
7.
闸门调节是灌区工程中经常采用的手段,闸门控制的研究对于节约能源、确保水利工程的正常运行、提高水资源的利用效率和节约用水具有重要的意义。以位山灌区二、三干渠节制闸为例,详细说明了闸门远程自动控制系统的工作原理和操作技术,重点介绍了应用效果。 相似文献
8.
9.
10.
传统的中小型拦河闸受冻害破坏较普遍而严重,新型的箱隔式拦河闸通过其总体布置,结果形式本身圆满地解决了复杂的冻害问题,不需外加任何特殊的防冻措施,箱隔式闸总体布置简单,阵线集中,薄弱环节少,受冻部位及面积小,基础在一个平面上均用水保温防冻,消除了基底法向冻胀力的危害,箱隔对称水平冻胀力大部分通过箱隔传递作用而衰减或平衡。 相似文献
11.
Neveen B. Abd El Mageed Amgad S. El Ansary Ashraf M. Ghanem Gamal H. Elsaeed 《Environmental Geology》2009,57(1):195-202
The Egyptian government is replacing the existing Naga Hammadi barrage, located across the Nile River some 450 km south of
Cairo, with the New Naga Hammadi barrage (NNHB) to incorporate a hydropower plant and to improve conditions for river traffic.
The new structure will lead to an increase in river water levels, both locally near the new barrage and upstream. The rise
in river water levels will in turn result in changes in groundwater levels in the aquifer system up and downstream of the
barrages. In this paper, an area is chosen, which is expected to suffer from a high groundwater table after the construction
of the NNHB, to investigate the problem and propose alternatives for lowering the groundwater levels. The study area is a
village called Bakhaness, with an area of 588 ha. It is located some 1.5 km upstream of the NNHB. A computer model (MicroFEM)
has been used to simulate the groundwater conditions before and after construction of the NNHB. Alternatives for lowering
the groundwater table are proposed, simulated and evaluated. The systems, which are assessed are a municipal sewer system,
a system of perforated pipes in urban areas, and tile drainage with different values of efficiency in agricultural areas. 相似文献
12.
13.
Drilling at the barrage site of a hydropower project usually gives a reasonable picture of the sub-surface rock mass condition. However, when the overburden (OB) comprising river borne materials is very thick and the basement rock is deep, the drilling results become unreliable. In the present case, the depth to the granitic gneiss basement is 45m from the river level and the height of the proposed diversion barrage is only 24.5 m. For this reason, stripping of the overburden up to the basement is not considered feasible. Cross-borehole seismic tomography (CST) was carried out at the barrage site to investigate the inclusions and structure of the OB material in order to facilitate a foundation design suitable for permeable formation. Three sets of CST surveys were carried out up to a depth of 30 m between the three vertical boreholes that were prepared at the vertices of an equilateral triangle with a separation of 17.8 m. The tomograms precisely imaged the nature and disposition of the different constituents of the overburden material. A lens shaped low velocity layer (LVL) with seismic velocity Vp=2000–2500 ms?1 was mapped at a depth of 14.5m from the surface. Hence, it was recommended to shift the barrage axis by 50 m towards the downstream side of the proposed axis. The outcome of this study proved valuable for the designer who finalised the foundation design. Successful application of CST in OB characterisation has reiterated the need of such studies for barrage site investigations particularly in the Himalayan terrain. 相似文献
14.
Impact of rehabilitation of Assiut barrage, Nile River, on groundwater rise in urban areas 总被引:1,自引:0,他引:1
Mohamed A. Dawoud Nahed E. El Arabi Ahmed R. Khater Jan van Wonderen 《Journal of African Earth Sciences》2006,45(4-5):395-407
To make optimum use of the most vital natural resource of Egypt, the River Nile water, a number of regulating structures (in the form of dams and barrages) for control and diversion of the river flow have been constructed in this river since the start of the 20th century. One of these barrages is the Assiut barrage which will require considerable repairs in the near future. The design of the rehabilitation of the barrage includes a headpond with water levels maintained at a level approximately 0.60 m higher than the highest water level in the headpond of the present barrage. This development will cause an increase of the seepage flow from the river towards the adjacent agricultural lands, Assiut Town and villages. The increased head pond level might cause a rise of the groundwater levels and impedance of drainage outflows. The drainage conditions may therefore be adversely affected in the so-called impacted areas which comprise floodplains on both sides of the Nile for about 70 km upstream of the future barrage. A rise in the groundwater table, particularly when high river levels impede drainage, may result in waterlogging and secondary salinization of the soil profile in agricultural areas and increase of groundwater into cellars beneath buildings in the urban areas. In addition, a rise in the groundwater table could have negative impact on existing sanitation facilities, in particular in the areas which are served with septic tanks. The impacts of increasing the headpond level were assessed using a three-dimensional groundwater model. The mechanisms of interactions between the Nile River and the underlying Quaternary aquifer system as they affect the recharge/discharge processes are comprehensively outlined. The model has been calibrated for steady state and transient conditions against historical data from observation wells. The mitigation measures for the groundwater rise in the urban areas have been tested using the calibrated mode. 相似文献
15.
阜阳华纺新天地桩基工程,原计划基坑底面施工调整为地面施工,增加了近14 m的空桩。为此,工程桩施工质量存在桩位、孔底沉渣厚度、钢筋笼位置、砼质量、砼桩顶标高等方面控制的相关问题。本文介绍了其施工情况,其经验可供类似工程借鉴。 相似文献
16.
海堤附近新建闸站常需要采用桩基进行软土地基处理,施工区域若存在隐伏块石层将影响桩基施工进度,增加施工成本,块石的空间分布特征亦对桩基施工工艺的选择起决定性作用。针对钻探法调查地下不规则分布块石盲目性大的问题,采用地质雷达与高密度电法为先导,并在物探异常区域辅以钻探验证的综合勘察技术对某闸站工程桩基施工区域地下块石进行了详查。依据勘察成果选用以旋挖钻为主的桩基施工方案,埋深小于6 m的成片块石区域采用井点降水与土方开挖回填相结合的施工工艺,局部埋深大于8 m的块石采用螺旋钻头或岩心钻头挖除,显著提升了桩基施工效率。结果表明:地质雷达与高密度电法用于探测地下浅部块石可优势互补,前者分辨率高,能体现部分零星块石堆的电磁异常,但块石与土层分界面难以判别,其异常特征表现为强振幅、波形杂乱,在纵向上伴随一定程度的多次反射;后者更适用于成片块石层的探测,较大粒径块石电阻率大于100 Ω·m,地下水位线附近的碎石电阻率小于30 Ω·m。研究成果可为软土施工区域地下深度6 m范围内块石的高精度探测以及对应桩基工程施工钻头的选择提供参考。 相似文献
17.
Eva Leitholdt Christoph Zielhofer Stefanie Berg‐Hobohm Katharina Schnabl Britta Kopecky‐Hermanns Jens Bussmann Joachim W. Hrtling Klaus Reicherter Katrin Unger 《Geoarchaeology》2012,27(1):88-104
The Central European watershed passes through the southern Franconian Jura in Bavaria, Germany. This principal watershed divides the Rhine/Main catchment and the Danube catchment. In the early Middle Ages, when ships were an important means of transportation, Charlemagne decided to connect these catchments by the construction of a canal known as the Fossa Carolina. In this paper, we present for the first time 14C data from the Fossa Carolina fill and document a high‐resolution stratigraphic record of the Carolingian and post‐Carolingian trench infilling. Our results provide clear evidence for peat layers in different levels of the trench infill, suggesting a chain of ponds. However, the majority of these peat layers yield mid‐Medieval and younger ages. The period of major peat growth was during the Medieval climatic optimum. Therefore, our preliminary results do not prove the use of the trench during Carolingian times. However, first results from the reconstruction of the Carolingian trench bottom support the hypothesis that the Fossa was primarily planned as a navigable chain of ponds and not as a continuous canal. In the eastern part of the trench, a dam is located that was postulated in former studies to be part of a barrage for supplying the Carolingian canal with water. New 14C data indicate much younger ages and do not support the Carolingian barrage concept. 相似文献
18.
P. L. Law I. N. Law H. H. Lau F. W. L. Kho 《International Journal of Environmental Science and Technology》2007,4(1):75-83
This study looks into the impacts of Sarawak Barrage (located in Kuching City, State of Sarawa Malaysia) flushing and flooding-in operations on upstream total suspended solids (TSS). Water samples were collected from three upstream stations on 17th, 18th and 19th of August 2000. During flushing, it was observed that TSS levels increased over a distance of 11 km upstream. Maximum TSS recorded 250 mg/L at 1.5 km, 120 mg/L at 6 km, and 85 mg/L at 11 km upstream. During flushing, TSS levels increased with depth, and upstream turbulence intensities were indirectly proportional to distance from barrage. During flooding-in operation, TSS decreased from 249 to 155 mg/L at 1.5 km near the bottom, while surface TSS decreased from 86 to 58 mg/L. Generally, during flooding-in operation, TSS increased from 90 to 116 mg/L between 6 and 11 km. During flooding-in operation, maximum bottom TSS recorded 216 mg/L at 6 km upstream. Differences between bottom and mid-depth TSS levels were relatively minimal ranging from 19 to 45 mg/L, whilst the maximum difference between mid-depth and surface TSS was as high as 78 mg/L. After 9 hours of gate closure, a well-mixed regime prevailed from 6 to 11 km upstream with TSS ranged from 35 to 47 mg/L at all the monitoring points regardless of depths. 相似文献
19.
介绍了梧桐庄矿大口径排水孔钻探成井、固井施工技术。该孔设计孔深646 m,终孔直径520 mm,落点坐标水平位移≯5 m,下入重达90余吨的Φ426 mm套管646 m,水泥固井。由于钻孔直径大,垂直度要求高,施工难度大,预防钻孔超斜、确保顺利安全下入Φ426 mm套管并固井是关键。通过采用小口径先导孔钻进再扩孔成井的施工方法,并采取合理的钻具组合和泥浆,制定有效的防斜技术和下套管措施等,顺利完成了施工任务,施工质量满足设计要求。 相似文献